I have been doing some Groovy development lately. I just spent a few minutes spinning around a quirky behavior that makes perfect sense to me now but at first had me scratching my head. Take a look at this...

That code is creating an instance of java.sql.Date and adding 2 days to it. My moment of confusion comes from the fact that after adding the 2 days the sqlDate reference no longer points to a java.sql.Date object but instead points to a java.util.Date object. Hmm... What is going on?

The operator overloading is being inherited into java.sql.Date from java.util.Date. The plus method in java.util.Date is returning a java.util.Date, which makes perfect sense. Since that method is inherited into java.sql.Date and not overridden then when it is invoked it returns a java.util.Date.